This invention relates to processes for converting carbon monoxide- and hydrogen-containing feedstocks, e.g., synthesis gas, to oxygenated products, e.g., esters, acids, acid anhydrides and mixtures thereof, and to processes for converting alcohol- and/or ether-containing feedstocks to oxygenated products, e.g., esters, acids, acid anhydrides and mixtures thereof.
It is known that carboxylic esters, acids, anhydrides and mixtures thereof can be prepared from feedstock comprising carbon monoxide and hydrogen gases by first forming an alcohol, such as methanol, and the corresponding ether (e.g., dimethyl ether), according to the theoretical reaction:
2CO+4H2=2CH3OH(CH3)2O+H2O
in the presence of a known alcohol conversion catalyst, and then separately converting the alcohol and/or ether in the presence of a known carbonylation catalyst into esters, acids, anhydrides and mixtures thereof containing one carbon atom more than the starting alcohol and ether, for example (theoretically):
CH3OH+CO=CH3COOH
or
(CH3)2O+2CO+H2O=2CH3COOH
or
CH3OH+(CH3)2O+3CO+H2O=3CH3COOH
Currently, commercial processes for the production of carboxylic acids from the carbonylation of an alcohol, ether and/or alcohol/ether mixture employ halide, e.g., iodide, promoters which are essential to obtain an acceptable level of catalyst activity. See, for example, U.S. Pat. Nos. 5,663,430, 5,750,007 and 5,672,743. Halide promoters are highly corrosive, requiring the use of exotic metals in the construction of the reaction vessels and expensive processing equipment (e.g., separation and refining equipment) to recover the homogeneous promoter from the product stream.
Known catalytic carbonylation processes for producing oxygenates which do not employ halide promoters are described in U.S. Pat. Nos. 5,218,140 and 5,330,955. Such processes involve the carbonylation of one or more alcohols or ethers to esters and carboxylic acids. The processes are carried out in the vapor state over a solid catalyst comprising a polyoxometalate anion in which the metal is at least one selected from Groups 5 and 6 (such as molybdenum, tungsten, vanadium, niobium, chromium and tantalum) complexed with at least one Group 8, 9 or 10 cation (such as Fe, Ru, Os, Co, Rh, Ir, Ni, Pd and Pt).
The oxygenates industry, particularly the acetic acid industry, would benefit significantly from a process that would simplify and/or eliminate complex, expensive equipment while simultaneously enabling more control over reaction rates and product selectivity. A solution enabling these advantages would provide a highly desirable industrial advance. Improved carbonylation catalysts for making oxygenates with respect to catalyst stability and carbonylation activity and selectivity would also be a highly desirable industrial advance.
This invention relates in part to a process for converting a feedstock stream comprising carbon monoxide and hydrogen to a product stream comprising at least one of an ester, acid, acid anhydride and mixtures thereof which comprises reacting said feedstock stream in the presence of a catalyst comprising an alcohol synthesis catalytic component and an alcohol carbonylation catalytic component, the composition of the components being different from one another and the composition of the alcohol carbonylation catalytic component comprising a solid super acid impregnated with a Group 7, 8, 9, 10 and/or 11 metal, a heteropoly acid impregnated with a Group 7, 8, 9, 10 and/or 11 metal, a clay impregnated with a Group 7, 8, 9, 10 and/or 11 metal, a zeolite impregnated with a Group 7, 8, 9, 10 and/or 11 metal or a molecular sieve impregnated with a Group 7, 8, 9, 10 and/or 11 metal, or mixtures thereof, and in the absence of a halide promoter, under conditions of temperature and pressure sufficient to produce said product stream. This process is preferably a gas or vapor phase reaction of synthesis gas to produce oxygenates therefrom, and is especially advantageous for the production of acetic acid and/or methyl acetate utilizing a single reaction vessel.
This invention also relates in part to a process for converting a feedstock stream comprising carbon monoxide and hydrogen to a product stream comprising at least one of an ester, acid, acid anhydride and mixtures thereof which comprises (a) reacting said feedstock stream in the presence of a catalyst under conditions of temperature and pressure sufficient to produce at least one of an alcohol, ether and mixtures thereof and (b) reacting carbon monoxide and said at least one of an alcohol, ether and mixtures thereof in the presence of a catalyst comprising a solid super acid impregnated with a Group 7, 8, 9, 10 and/or 11 metal, a heteropoly acid impregnated with a Group 7, 8, 9, 10 and/or 11 metal, a clay impregnated with a Group 7, 8, 9, 10 and/or 11 metal, a zeolite impregnated with a Group 7, 8, 9, 10 and/or 11 metal or a molecular sieve impregnated with a Group 7, 8, 9, 10 and/or 11 metal, or mixtures thereof, and in the absence of a halide promoter, under conditions of temperature and pressure sufficient to produce said product stream. This process is preferably a gas or vapor phase reaction, and is especially advantageous for the production of acetic acid and/or methyl acetate utilizing separate reaction vessels for steps (a) and (b).
This invention further relates in part to a process for converting a feedstock stream comprising at least one of an alcohol and ether and mixtures thereof to a product stream comprising at least one of an ester, acid, acid anhydride and mixtures thereof which comprises reacting said feedstock stream and carbon monoxide in the presence of a catalyst comprising a solid super acid impregnated with a Group 7, 8, 9, 10 and/or 11 metal, a heteropoly acid impregnated with a Group 7, 8, 9, 10 and/or 11 metal, a clay impregnated with a Group 7, 8, 9, 10 and/or 11 metal, a zeolite impregnated with a Group 7, 8, 9, 10 and/or 11 metal or a molecular sieve impregnated with a Group 7, 8, 9, 10 and/or 11 metal, or mixtures thereof, and in the absence of a halide promoter, under conditions of temperature and pressure sufficient to produce said product stream. This process is preferably a gas or vapor phase reaction, and is especially advantageous for the production of acetic acid and/or methyl acetate utilizing one or more reaction vessels.
This invention yet further relates in part to a process for converting a feedstock stream comprising at least one of an alcohol and ester and mixtures thereof to a product stream comprising at least one of an ether, acid, acid anhydride and mixtures thereof which comprises reacting said feedstock stream in the presence of a catalyst comprising an ester hydrolysis catalytic component and an alcohol dehydration catalytic component under conditions of temperature and pressure sufficient to produce said product stream. This process is preferably a gas or vapor phase reaction of an alcohol and ester to produce an ether and acid therefrom, and is especially advantageous for the production of acetic acid and/or dimethyl ether utilizing a single reaction vessel, e.g., a coupled hydrolysis/dehydration reactor.
The processes and catalysts of this invention are particularly unique in that they enable the production of oxygenates from carbon monoxide- and hydrogen-containing feedstocks or alcohol- and/or ether-containing feedstocks in one or more reactors and in which no halides are required in the liquid or vapor phases of the feedstock streams and/or recycle streams of the processes, thus providing substantial economic benefits in the design of equipment to carry out the processes. Moreover, the multicomponent catalysts of this invention enable substantial control over the composition of the reaction product simply by varying the composition of one component of the catalyst and/or its concentration relative to the other component. Further, the processes and catalysts of this invention enable the production of oxygenates under one or more sets of reaction conditions. The carbonylation catalysts of this invention provide improved catalyst stability and improved carbonylation activity and selectivity as described herein.